Scientific Study

RATIONALE: 'Generic' immunoassays for peanut cannot discriminate between allergen levels in peanut derived food products or therapeutics. Clinical trials of oral immunotherapy are strengthened by using standardized peanut preparations, with defined doses of major allergens. OBJECTIVE: This paper describes measurement of Ara h 1, Ara h 2 and Ara h 6 in peanut foods and in peanut flour extracts used for allergy diagnosis and oral immunotherapy. METHODS: Monoclonal antibody-based enzyme immunoassays for Ara h 1, Ara h 2 and Ara h 6 were used to compare allergen levels in peanut (n=19) and tree nut (n=16) butter, peanut flour (n=11); oils (n=8); extracts used for diagnosis and oral immunotherapy (n=5); and the National Institute for Standards and Technology Peanut Butter Standard Reference Material® 2387. RESULTS: Roasted peanut butters contained 991-21,406μg/g Ara h 1 and exceeded Ara h 2 and Ara h 6 levels by 2-4 fold. Similarly, NIST SRM 2387 contained 11,275μg/g Ara h 1; 2,522μg/g Ara h 2 and 2,036μg/g Ara h 6. In contrast, peanut flours contained 787-14,631μg/g Ara h 2 and exceeded Ara h 1 levels by 2-20 fold. Flour extracts used for oral immunotherapy contained 394-505μg/ml Ara h 1, 1,187-5,270μg/ml Ara h 2 and 1,104-8,092μg/ml Ara h 6. In most cases, specific peanut allergens were not detected in tree nut butters or peanut oils. CONCLUSIONS: The results show marked differences in specific peanut allergen profiles in peanut butter, flour and peanut preparations for clinical use. Roasting may increase Ara h 1 levels in peanut butter. Variability in allergen levels could affect the outcome of clinical trials of peanut oral immunotherapy, especially with respect to Ara h 1. Specific allergen measurements will improve standardization and provide accurate dosing of peanut preparations that are being used for oral immunotherapy.